Clinical Biochemistry 37 (2004) 10 – 13
In vitro analysis of human transplacental transport of desmopressin Joel G. Ray, a,* Rada Boskovic, b Brenda Knie, b Marjie Hard, b Galina Portnoi, b and Gideon Koren b,c a
Obstetrical Medicine, Department of Medicine, and Inner City Health Research Program, St. Michael’s Hospital, Toronto, ON, Canada b Motherisk Program, The Hospital for Sick Children, Toronto, ON, Canada c Department of Pediatrics and Pharmacology, The Hospital for Sick Children, Toronto, ON, Canada Received 1 July 2002; received in revised form 26 August 2003; accepted 30 September 2003
Abstract Objective: Desmopressin (DDAVP) therapy may be required during pregnancy, but there are limited data about its safety. We wished to verify whether DDAVP is transported across the human placenta. Methods: Using the in vitro human placental cotyledon perfusion model, we performed serial measurements of maternal and fetal DDAVP concentrations. After introducing the drug into the maternal circulation at estimated baseline therapeutic (30 pg/ml) and supratherapeutic (16,000 and 60,000 pg/ml) concentrations, we measured the rate of transplacental drug transfer up to 2 h. Results: There was no detectable transport of DDAVP at a 30 pg/ml concentration, and the maternal drug concentration remained stable over time. At a much higher maternal concentration of 60,000 pg/ml, the mean peak fetal DDAVP concentration was 2990 pg/ml, equivalent to 4.8% of the baseline maternal concentration. Conclusion: At a therapeutic maternal drug concentration, DDAVP does not appear to cross the placenta within detectable limits. At much higher drug concentrations, DDAVP may cross the placenta in a small amount. Future in vitro clinical studies should attempt to reproduce these findings. D 2003 The Canadian Society of Clinical Chemists. All rights reserved. Keywords: Desmopressin; DDAVP; Arginine vasopressin; Placenta; Placental perfusion; von Willebrand disease; Diabetes insipidus; Pregnancy; Fetus
Background Desmopressin, desamino-8-D-arginine-vasopressin (DDAVP), is a synthetic analog of the naturally occurring antidiuretic hormone, 8-arginine vasopressin (AVP) (Fig. 1). DDAVP is effective in the treatment of both central diabetes insipidus and some types of von Willebrand disease [1,2]. Since long-term therapy during pregnancy is often required, knowledge about the fetal safety of DDAVP is of importance. In a previous systematic review, no significant increase in adverse events was found among 49 infants born to mothers who had received therapeutic doses of DDAVP during pregnancy, even after extended periods of time [3]. Although reports of DDAVP use during pregnancy suggest that it is safe, there are no data regarding the
transplacental transfer of this drug. Such information has clinical importance for two contrasting reasons. First, if it does not cross the placenta, then this provides further evidence in support of a probable lack of fetal harm. Conversely, if maternally administered DDAVP can be delivered to the fetus in effective doses, then there emerges a theoretical basis for future research on the use of this agent. For example, in the presence of fetal alloimmune thrombocytopenia [4], maternally administered DDAVP might be used to reduce the risk of fetal hemorrhage [5] during delivery or with diagnostic cordocentesis. We conducted an in vitro perfusion study, using a human placental cotyledon model, to characterize the human transplacental transfer of DDAVP.
Methods * Corresponding author. Inner City Health Research Unit, St. Michael’s Hospital, 30 Bond Street, Toronto, ON, Canada M5B 1W8. Fax: +1-416864-5485. E-mail address:
[email protected] (J.G. Ray).
We used the human placental cotyledon perfusion model, as previously described [6]. Term placentae were obtained from women experiencing an uncomplicated pregnancy,
0009-9120/$ - see front matter D 2003 The Canadian Society of Clinical Chemists. All rights reserved. doi:10.1016/j.clinbiochem.2003.09.006
J.G. Ray et al. / Clinical Biochemistry 37 (2004) 10–13
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Fig. 1. Molecular structure (molecular weight) of 8-arginine vasopressin, synthetic DDAVP and oxytocin.
followed by elective vaginal or Cesarean delivery. Each placenta was immediately transported to the laboratory in an iced heparinized phosphate-buffered saline solution. Independent maternal and fetal circulations were established to a peripheral placental lobule within 30 min of delivery. A chorionic artery and vein supplying a peripheral placental lobule were selected and cannulated. Flow rates were maintained at 13– 15 ml/min (maternal side) and 3– 4 ml/ min (fetal side). Fetal inflow pressure was measured in the fetal arterial circuit proximal to its insertion into the cannulated chorionic artery. The perfusate, tissue culture medium M199, was maintained at 37jC and contained the following ingredients: heparin (2000 U/l), kanamycin (100 mg/l), glucose (1.0 g/l), antipyrine (maternal, 0.188 g/l) and dextran 40 (fetal, 30 g/l; maternal 7.5 g/l). Sodium bicarbonate was added to maintain physiologic pH values of 7.35 (maternal) and 7.4 (fetal). The perfusates were equilibrated with 95% O2 –5% CO2 (maternal) and 95% N2 – 5% CO2 (fetal). DDAVP injectate (Ferring Inc., Toronto, Canada) was used in all perfusion experiments. After residual blood was cleared from the vessels and intervillous space, a 1-h ‘‘closed-circuit’’ (recirculated) control period preceded the experimental period. During the control and experimental periods, both oxygen and glucose consumption and lactate production were measured to confirm maintained tissue energy metabolism. The physical integrity of the placental preparation was assessed by monitoring the stability of the fetal perfusion pressure and volume loss from the fetal reservoir. A pressure rise or loss of greater than 10 mm Hg, or a volume loss of greater than 3 ml/h, were criteria for rejection of the preparation. In each
experiment, the parameters of glucose utilization, lactate production, antipyrine clearance and oxygen consumption were constant during experimental and control periods, and were consistent with previously published standards [6– 8]. A total of six experiments were completed. After each 1h control period, the perfusates in both the maternal and fetal circulations were replaced with fresh media. In the first two experiments, the maternal perfusate was primed at a therapeutic DDAVP concentration of 30 pg/ml, while the latter four experiments were done at supratherapeutic concentrations of 16,000 and 60,000 pg/ml, respectively. Samples were obtained from the fetal and maternal reservoirs at 0, 10, 20, 30, 60 and 120 min, from which we measured concentrations of DDAVP, antipyrine, lactate, oxygen and glucose. All samples were stored at 80jC and then transported on dry ice to Ferring’s Bioanalytical Department laboratory in Malmo¨, Sweden. DDAVP concentrations were determined using a highly specific radioimmunoassay, with a lower limit of quantification of 5 pg/ml. The precision and accuracy were each within the 15% standard limit, both for inter- and intra-assay measurements.
Results During the closed-circuit control run, in the absence of placental tissue, there was no appreciable difference or change in DDAVP concentrations between the maternal and fetal compartments (Table 1). At a maternal DDAVP concentration of 30 pg/ml, there was no measurable drug quantity in the fetal circulation over
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J.G. Ray et al. / Clinical Biochemistry 37 (2004) 10–13
Table 1 Maternal and fetal DDAVP concentrations over time, according to three baseline drug doses Baseline DDAVP concentration in maternal compartment (pg/ml)
Experiment number
60,000
Control runa
30
1 2 1 and 2 (averaged)
16,000
3 4 3 and 4 (averaged)
60,000
5 6 5 and 6 (averaged)
DDAVP concentration (pg/ml)
Time (min)
Maternal Fetal Maternal Fetal Maternal Fetal Maternal Fetal Maternal Fetal Maternal Fetal Maternal Fetal Maternal Fetal Maternal Fetal Maternal Fetal
47,600 56,100 –
